The mechanism of heat transfer is also different – conductive heat in the case of our elements, compared with a combination of radiant & convective heat for coiled wire elements. Where the coiled wire element is enclosed in a sheath, the element wire firstly has to raise the temperature of the magnesium oxide powder (there as electrical insulation, but also an effective thermal insulation!) as well as the enclosing metal sheath. Accordingly, the operating temperature of the resistor wire is considerably higher than the external surface temperature of the enclosing sheath. As an illustration, an oven operating at 275-300°C and heated by radiant/ convective heat from conventional sheathed coiled wire elements, would typically operate at 400-450°C sheath surface temperature, necessitating an element surface temperature of around 550-600°C.

In contrast, our intimate contact elements would only need to operate at a surface temperature of 300-325°C to maintain the same operating oven temperature.

From Stefan Boltzman law, there is a quadratic relationship between the energy required to maintain a radiant temperature source and the temperature level concerned.

Apart from this difference in respective operating temperatures between the 2 types of elements, there is also a significant difference in mass. Whereas a typical sheathed coiled wire used in an oven will have a total mass of ca 400gms, a typical comparable sprayed element will weigh only ca 25gms. This very large difference in mass, allied with the difference in specific heats of the materials used and the much higher respective operating temperatures for each type of element, indicates a 40 fold difference in energy requirements between the two simply to reach the required operating temperatures. (Q = M.C.deltaT°). Since the ovens are then vented, there will be a corresponding energy imbalance to maintain the respective operating temperatures.